1. Field of the Invention
The invention relates to a head up display with a device for producing a focused light flux, having a light source and having an image reproduction apparatus including light valves.
2. Description of the Prior Art
In order to convey information to vehicle drivers without the need for them to avert their gaze from the road to be driven or the air space to be flown, so-called head up displays have become known that are used to fade in an image representing information into the windshield of a vehicle. In order for the image still to remain visible in bright ambient light, there is an additional need for it to have a high luminous density. Focused light fluxes are also required for other illumination purposes, for example as reading lamps or as emitters for show-windows and expositions.
Devices for producing a focused light flux have already been disclosed in U.S. Pat. Nos. 5,836,676, 5,043,716 and 5,617,131 in an application for a display, in each case. A luminaire with focusing of the light beam is known from U.S. Pat. No. 4,935,665. However, the arrangements shown exhibit scarcely any suitability for use in a head-up display, because of their respective focusing and scattering characteristics.